Following a final failed attempt by Senate Republicans to kill the Iran nuclear agreement Thursday, the administration moved aggressively toward putting it into effect, naming a new czar to oversee implementation and announcing that President Obama would issue waivers suspending all U.S. nuclear-related sanctions on Oct. 18.

The waivers will not go into effect until what the agreement itself calls “Implementation Day,” when the International Atomic Energy Agency certifies that Iran has complied with all of its obligations — including removal of 98 percent of its enriched uranium stockpile, shutting down its underground enrichment facility and rendering inoperative the core of a plutonium-capable reactor.

Senior administration officials said those processes could take well into 2016 once they begin next month, under the terms of the deal completed in July.

Secretary of State John F. Kerry appointed a career foreign service officer, Stephen D. Mull, as implementation coordinator among U.S. agencies and negotiating partners, reporting directly to the secretary’s office. Before his most recent job as U.S. ambassador to Poland, Mull played a key role in early negotiations with Iran.

“I have always said that, as important as it was to negotiate the nuclear deal with Iran, implementing it was going to be even more crucial in meeting our national security objectives,” Kerry said in announcing Mull’s appointment.

Thursday was the deadline, under legislation negotiated between Obama and Congress, for lawmakers to vote a resolution of disapproval of the deal. If such a vote could be sustained with an override of Obama’s promised veto, it would have prevented the president from exercising provisions allowing him to waive sanctions provisions.

Senate Democrats for the third time blocked a resolution vote, preventing the Republican-backed measure from getting the 60 votes it needed to advance. Thursday’s failed proposal would have also barred any waivers unless Iran recognized Israel and released four American prisoners it is holding.

Several Democrats who had voted for the previous two measures joined in rejecting Thursday’s attempt, saying that the Israel and prisoner provisions were outside the scope of what Congress originally agreed to review.

Senate Majority Leader Mitch McConnell (R-Ky.) said that the Democrats had “made their choice” and would be as responsible as Obama for a deal that would allow billions of dollars to “flow into Iranian coffers to use for terrorism.”

In an angrily worded statement after the vote, Sen. Dianne Feinstein (D-Calif.) called the Republican effort “nothing more than an attempt to extract a political price” from those who have supported the deal all along.

Under provisions of the agreement, it must be formally adopted by all parties — including the United States, the five other world powers who participated in the negotiations, and Iran — 90 days after the U.N. Security Council approved it in July. That day is Oct. 18.

From then on, said one of several senior administration officials who briefed reporters on implementation steps, “the ball is in Iran’s court.” The officials spoke on the condition of anonymity under rules set by the State Department.

The IAEA must verify all compliance steps in the deal have been taken, along with verification that Iran has satisfied the agency’s questions about previous nuclear activities at military installations, “before sanctions relief is offered,” an administration official said. “Implementation day is unknown at this point.”

Signing of the waivers in advance — along with steps expected on Oct. 18 by the European Union to prepare to lift its own nuclear-related sanctions — were included in the deal as a demonstration of good faith as Iran begins its dismantlement.

On the day sanctions are removed, Iranian oil sales and financial transactions with much of the world are free to resume and frozen Iranian assets will be released, although prohibitions against arms sales and the transfer of missile technology will remain in effect for five and eight years, respectively.

U.S. interaction with Iran will be limited as sanctions related to Iranian support for terrorism will remain in effect. The U.S. waivers, which the president must renew every three to six months, can be reversed if Iran fails to comply with the agreement.

The administration must also now turn its attention to preventing the Republican-led Congress from voting new sanctions against Iran or otherwise trying to scotch the deal. Obama has promised to assuage Israeli opposition to it with new measures to buttress Israeli defenses. One step in that direction, officials said, is Obama’s invitation to Israeli Prime Minister Benjamin Netanyahu to the White House in November.